The present invention relates to a gearing unit particularly for use with mining equipment.
A known form of gearing unit employs a sensor which senses overloads and operates a clutch to disconnect the output shaft from the input shaft. German patent specification No. 3043237 (which has an equivalent GB No. 2088442) describes a drive or gearing unit of this type. In this known construction, a strain gauge incorporated in the gear train is used to provide a load signal which serves to operate the clutch. Where the output shaft is used to drive a plough chain the clutch must disengage the drive rapidly and reliably to ensure the chain does not break should overloading occur. Tests have shown that the response time is determined by the minimum distance of the plough to the chain wheel and the gearing unit, i.e. when the plough is at the end of its travel. With a normal displacement speed of 2-3 meters per second and a maximum elongation of the chain of 1.4% the necessarily quick response time cannot be achieved with known constructions.
A general object of the present invention is to provide an improved gearing unit.